U.S. patent application number 10/600435 was filed with the patent office on 2004-03-11 for head arm assembly and disk drive device with the head arm assembly.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Honda, Takashi, Kurihara, Katsuki, Kuwajima, Hideki, Matsuoka, Kaoru, Wada, Takeshi, Wu, Kai.
Application Number | 20040047077 10/600435 |
Document ID | / |
Family ID | 29996861 |
Filed Date | 2004-03-11 |
United States Patent
Application |
20040047077 |
Kind Code |
A1 |
Honda, Takashi ; et
al. |
March 11, 2004 |
Head arm assembly and disk drive device with the head arm
assembly
Abstract
An HAA includes a head slider having at least one head element,
an arm member for supporting the head slider at one end section, an
actuator, mounted to the other end section of the arm member, for
rotationally moving the arm member in a direction substantially
parallel with a recording medium surface around a horizontal
rotation axis of the arm member, and a load generation unit for
generating a load for energizing the head slider in a direction to
the recording medium surface by rotationally moving the arm member
in a direction substantially orthogonal to the recording medium
surface around a vertical rotation axis. The position of the center
of gravity of the HAA is located at a different position from the
vertical rotation axis on a center axis of the arm member.
Inventors: |
Honda, Takashi; (Tokyo,
JP) ; Kurihara, Katsuki; (Tokyo, JP) ; Wada,
Takeshi; (Tokyo, JP) ; Wu, Kai; (Guandong,
CN) ; Matsuoka, Kaoru; (Osaka, JP) ; Kuwajima,
Hideki; (Kyoto, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TDK CORPORATION
Tokyo
JP
SAE Magnetics (H.K.) Ltd.
Kwai Chung
HK
Matsushita Electric Industrial Co., Ltd.
Osaka
JP
|
Family ID: |
29996861 |
Appl. No.: |
10/600435 |
Filed: |
June 23, 2003 |
Current U.S.
Class: |
360/244.2 ;
G9B/5.151; G9B/5.231 |
Current CPC
Class: |
G11B 5/4826 20130101;
G11B 5/6005 20130101 |
Class at
Publication: |
360/244.2 |
International
Class: |
G11B 005/48 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2002 |
JP |
2002-189844 |
Claims
What is claimed is:
1. A head arm assembly comprising: a head slider having at least
one head element; an arm member for supporting the head slider at
one end section; an actuator, mounted to the other end section of
the arm member, for rotationally moving the arm member in a
direction substantially parallel with a recording medium surface
around a horizontal rotation axis of the arm member; and a load
generation means for generating a load for energizing said head
slider in a direction to the recording medium surface by
rotationally moving said arm member in a direction substantially
orthogonal to said recording medium surface around a vertical
rotation axis, the position of the center of gravity of the head
arm assembly being located at a different position from said
vertical rotation axis on a center axis of said arm member.
2. The head arm assembly as claimed in claim 1, wherein a force
applied to said head slider by a rotational moment occurring due to
an applied impact acceleration and a displacement of said position
of the center of gravity is set to be not more than negative
pressure or positive pressure occurring to an air bearing surface
of said head slider due to rotation of said recording medium.
3. The head arm assembly as claimed in claim 1, wherein said
position of the center of gravity is located at a position between
said actuator and said vertical rotation axis.
4. The head arm assembly as claimed in claim 3, wherein said
position of the center of gravity is a position which substantially
satisfies L.sub.2=M.sub.1.times.L.sub.1/M.sub.2, where M.sub.1 is a
mass at a load point to said head slider, M.sub.2 is a mass at said
position of the center of gravity, L.sub.1 is a distance between a
load point to said head slider and said vertical rotation axis,
L.sub.2 is a distance between said vertical rotation axis and said
position of the center of gravity.
5. The head arm assembly as claimed in claim 3, wherein when said
position of the center of gravity is at a position which
substantially satisfies L.sub.2>M.sub.1.times.L.sub.1/M.sub.2,
where M.sub.1 is a mass at a load point to said head slider,
M.sub.2 is a mass at said position of the center of gravity,
L.sub.1 is a distance between a load point to said head slider and
said vertical rotation axis, L.sub.2 is a distance between said
vertical rotation axis and said position of the center of gravity,
an air bearing surface of said head slider is set so that positive
pressure occurring to the air bearing surface due to rotation of
said recording medium is not less than a product of an inertial
force obtained from a mass of a part from said position of center
of gravity of the head arm assembly to said head slider and an
applied impact acceleration.
6. The head arm assembly as claimed in claim 3, wherein when said
position of the center of gravity is at a position which
substantially satisfies L.sub.2<M.sub.1.times.L.sub.1/M.sub.2,
where M.sub.1 is a mass at a load point to said head slider,
M.sub.2 is a mass at said position of the center of gravity,
L.sub.1 is a distance between a load point to said head slider and
said vertical rotation axis, L.sub.2 is a distance between said
vertical rotation axis and said position of the center of gravity,
an air bearing surface of said head slider is set so that negative
pressure occurring to the air bearing surface due to rotation of
said recording medium is not less than a product of an inertial
force obtained from a mass of a part from said position of center
of gravity of the head arm assembly to said head slider and an
applied impact acceleration.
7. The head arm assembly as claimed in claim 1, wherein said
position of the center of gravity is located at a position between
said head slider and said vertical rotation axis.
8. The head arm assembly as claimed in claim 7, wherein when said
position of the center of gravity is at a position which
substantially satisfies L.sub.2<M.sub.1.times.L.sub.1/M.sub.2,
where M.sub.1 is a mass at a load point to said head slider,
M.sub.2 is a mass at said position of the center of gravity,
L.sub.1 is a distance between a load point to said head slider and
said vertical rotation axis, L.sub.2 is a distance between said
vertical rotation axis and said position of the center of gravity,
an air bearing surface of said head slider is set so that negative
pressure occurring to the air bearing surface due to rotation of
said recording medium is not less than a product of an inertial
force obtained from a mass of a part from said position of center
of gravity of the head arm assembly to said head slider and an
applied impact acceleration.
9. The head arm assembly as claimed in claim 1, wherein said
horizontal rotation axis is provided at a horizontal bearing part
located at a midpoint of said arm member, and said vertical
rotation axis comprises a protuberance provided in the vicinity of
the horizontal bearing part.
10. The head arm assembly as claimed in claim 9, wherein said load
generation means comprises a leaf spring connected to said
horizontal bearing part and to said arm member.
11. The head arm assembly as claimed in claim 1, wherein said arm
member comprises a support arm having rigidity, and a flexure
having elasticity, which is supported at one end section of the
support arm and for controlling a flying attitude of said head
slider, and the head slider is fixed on the flexure.
12. The head arm assembly as claimed in claim 11, wherein said arm
member further comprises a load beam having rigidity and including
a load protrusion for applying load to said head slider, said
flexure being fixed on the load beam.
13. A disk drive device including at least one head arm assembly
that comprises: a head slider having at least one head element; an
arm member for supporting the head slider at one end section; an
actuator, mounted to the other end section of the arm member, for
rotationally moving the arm member in a direction substantially
parallel with a recording medium surface around a horizontal
rotation axis of the arm member; and a load generation means for
generating a load for energizing said head slider in a direction to
the recording medium surface by rotationally moving said arm member
in a direction substantially orthogonal to said recording medium
surface around a vertical rotation axis, the position of the center
of gravity of the head arm assembly being located at a different
position from said vertical rotation axis on a center axis of said
arm member.
14. The disk drive device as claimed in claim 13, wherein a force
applied to said head slider by a rotational moment occurring due to
an applied impact acceleration and a displacement of said position
of the center of gravity is set to be not more than negative
pressure or positive pressure occurring to an air bearing surface
of said head slider due to rotation of said recording medium.
15. The disk drive device as claimed in claim 13, wherein said
position of the center of gravity is located at a position between
said actuator and said vertical rotation axis.
16. The disk drive device as claimed in claim 15, wherein said
position of the center of gravity is a position which substantially
satisfies L.sub.2=M.sub.1.times.L.sub.1/M.sub.2, where M.sub.1 is a
mass at a load point to said head slider, M.sub.2 is a mass at said
position of the center of gravity, L.sub.1 is a distance between a
load point to said head slider and said vertical rotation axis,
L.sub.2 is a distance between said vertical rotation axis and said
position of the center of gravity.
17. The disk drive device as claimed in claim 15, wherein when said
position of the center of gravity is at a position which
substantially satisfies L.sub.2>M.sub.1.times.L.sub.1/M.sub.2,
where M.sub.1 is a mass at a load point to said head slider,
M.sub.2 is a mass at said position of the center of gravity,
L.sub.1 is a distance between a load point to said head slider and
said vertical rotation axis, L.sub.2 is a distance between said
vertical rotation axis and said position of the center of gravity,
an air bearing surface of said head slider is set so that positive
pressure occurring to the air bearing surface due to rotation of
said recording medium is not less than a product of an inertial
force obtained from a mass of a part from said position of center
of gravity of the head arm assembly to said head slider and an
applied impact acceleration.
18. The disk drive device as claimed in claim 15, wherein when said
position of the center of gravity is at a position which
substantially satisfies L.sub.2<M.sub.1.times.L.sub.1/M.sub.2,
where M.sub.1 is a mass at a load point to said head slider,
M.sub.2is a mass at said position of the center of gravity, L.sub.1
is a distance between a load point to said head slider and said
vertical rotation axis, L.sub.2 is a distance between said vertical
rotation axis and said position of the center of gravity, an air
bearing surface of said head slider is set so that negative
pressure occurring to the air bearing surface due to rotation of
said recording medium is not less than a product of an inertial
force obtained from a mass of a part from said position of center
of gravity of the head arm assembly to said head slider and an
applied impact acceleration.
19. The disk drive device as claimed in claim 13, wherein said
position of the center of gravity is located at a position between
said head slider and said vertical rotation axis.
20. The disk drive device as claimed in claim 19, wherein when said
position of the center of gravity is at a position which
substantially satisfies L.sub.2<M.sub.1.times.L.sub.1/M.sub.2,
where M.sub.1 is a mass at a load point to said head slider,
M.sub.2is a mass at said position of the center of gravity, L.sub.1
is a distance between a load point to said head slider and said
vertical rotation axis, L.sub.2 is a distance between said vertical
rotation axis and said position of the center of gravity, an air
bearing surface of said head slider is set so that negative
pressure occurring to the air bearing surface due to rotation of
said recording medium is not less than a product of an inertial
force obtained from a mass of a part from said position of center
of gravity of the head arm assembly to said head slider and an
applied impact acceleration.
21. The disk drive device as claimed in claim 13, wherein said
horizontal rotation axis is provided at a horizontal bearing part
located at a midpoint of said arm member, and said vertical
rotation axis comprises a protuberance provided in the vicinity of
the horizontal bearing part.
22. The disk drive device as claimed in claim 21, wherein said load
generation means comprises a leaf spring connected to said
horizontal bearing part and to said arm member.
23. The disk drive device as claimed in claim 13, wherein said arm
member comprises a support arm having rigidity, and a flexure
having elasticity, which is supported at one end section of the
support arm and for controlling a flying attitude of said head
slider, and the head slider is fixed on the flexure.
24. The disk drive device as claimed in claim 23, wherein said arm
member further comprises a load beam having rigidity and including
a load protrusion for applying load to said head slider, said
flexure being fixed on the load beam.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a head arm assembly (HAA)
having a recording and/or a reproducing head such as a flying type
thin-film magnetic head or a flying type optical head, and to a
disk drive device with the HAA.
DESCRIPTION OF THE RELATED ART
[0002] In a magnetic disk drive device, a magnetic head slider for
writing magnetic information into and/or reading magnetic
information from a magnetic disk is in general formed on a magnetic
head slider flying in operation above a rotating magnetic disk. The
slider is fixed at a top end section of an HAA.
[0003] The conventional HAA includes a support arm with high
rigidity, a voice coil motor (VCM) that is an actuator to
rotationally move this support arm in parallel with a magnetic disk
surface, a suspension having elasticity, which is fixed to a tip
end of the support arm, and a magnetic head slider mounted to a top
end section of the suspension, and it is constructed so that a load
applied to the magnetic head slider in a direction to the magnetic
disc surface generated with a leaf spring provided at the
suspension itself, or a leaf spring provided at a connecting
section of the suspension and the support arm.
[0004] In the HAA with the conventional structure as described
above, the magnetic head slider is mounted to the suspension at the
tip of the leaf spring, and therefore when an impact is applied
thereto from outside, there is a fear that the magnetic head slider
is strongly vibrated and collided against the magnetic disk
surface, and gives a damage to the disk surface.
[0005] In order to improve resistance of the HAA with the
conventional structure against the impact, an HAA with a new
structure, in which a main part of the HAA is constructed by an arm
member with high rigidity, a magnetic head slider is mounted to one
end section of the arm member while a VCM is mounted to the other
end section, a support point to make it possible to rotationally
move in a direction orthogonal to the surface of the magnetic disc
is provided in the middle of the one end and the other end of the
arm member, and a leaf spring for load generation is mounted to
that section, is researched and developed (not known at the time of
this application).
SUMMARY OF THE INVENTION
[0006] It is therefore an object of the present invention to
provide a new structure HAA capable of enhancing having an impact
resistance, and a disk drive device including the HAA.
[0007] According to the present invention, an HAA includes a head
slider having at least one head element, an arm member for
supporting the head slider at one end section, an actuator, mounted
to the other end section of the arm member, for rotationally moving
the arm member in a direction substantially parallel with a
recording medium surface around a horizontal rotation axis of the
arm member, and a load generation unit for generating a load for
energizing the head slider in a direction to the recording medium
surface by rotationally moving the arm member in a direction
substantially orthogonal to the recording medium surface around a
vertical rotation axis. The position of the center of gravity of
the HAA is located at a different position from the vertical
rotation axis on a center axis of the arm member.
[0008] Also, according to the present invention, a disk drive
device including at least one of the HAA is further provided.
[0009] The head slider and the actuator such as a VCM are mounted
to respective end sections of an arm member, and the horizontal
rotation axis is located between them. The arm member is
constructed to be able to rotationally move in the direction
substantially orthogonal to the recording medium surface around the
vertical rotation axis, and the head slider is biased in the
direction of the recording medium surface by the load generation
unit. In the HAA with such a new structure, the position of the
center of gravity is set to be displaced to a different position
from the vertical rotation axis on the center axis of the arm
member. By appropriately selecting the displacement of this
position of the center of gravity, it becomes possible to keep the
load applied to the head slider substantially constant irrespective
of the positive and negative direction and the value of the impact
acceleration applied from outside, and it becomes possible to
enhance impact resistance dramatically. By adjusting the displacing
amount and the positive and negative direction of the position of
the center of gravity, the load property applied to the head slider
with respect to the impact acceleration applied from outside can be
varied. Accordingly, it becomes possible to compensate positive
pressure or negative pressure occurring to an air bearing surface
(ABS) of the head slider during rotation of the recording medium
with this displacing amount. As a result, degree of freedom of the
ABS design of the head slider is improved to a large extent, and it
also becomes possible to obtain a desired flying property for the
head slider with the ABS area being very small.
[0010] It is preferred that a force applied to the head slider by a
rotational moment occurring due to an applied impact acceleration
and a displacement of the position of the center of gravity is set
to be not more than negative pressure or positive pressure
occurring to an ABS of the head slider due to rotation of the
recording medium.
[0011] It is also preferred that the position of the center of
gravity is located at a position between the actuator and the
vertical rotation axis.
[0012] It is preferred that the position of the center of gravity
is a position which substantially satisfies
L.sub.2=M.sub.1.times.L.sub.1/M.su- b.2, where M.sub.1 is a mass at
a load point to the head slider, M.sub.2 is a mass at the position
of the center of gravity, L.sub.1 is a distance between a load
point to the head slider and the vertical rotation axis, L.sub.2 is
a distance between the vertical rotation axis and the position of
the center of gravity.
[0013] It is further preferred that when the position of the center
of gravity is at a position which substantially satisfies
L.sub.2>M.sub.1.times.L.sub.1/M.sub.2, an ABS of the head slider
is set so that positive pressure occurring to the ABS due to
rotation of the recording medium is not less than a product of an
inertial force obtained from a mass of a part from the position of
center of gravity of the head arm assembly to the head slider and
an applied impact acceleration.
[0014] It is preferred that when the position of the center of
gravity is at a position which substantially satisfies
L.sub.2<M.sub.1.times.L.su- b.1/M.sub.2, where M.sub.1 is a mass
at a load point to the head slider, M.sub.2 is a mass at the
position of the center of gravity, L.sub.1 is a distance between a
load point to the head slider and the vertical rotation axis,
L.sub.2 is a distance between the vertical rotation axis and the
position of the center of gravity, an ABS of the head slider is set
so that negative pressure occurring to the ABS due to rotation of
the recording medium is not less than a product of an inertial
force obtained from a mass of a part from the position of center of
gravity of the head arm assembly to the head slider and an applied
impact acceleration.
[0015] It is also preferred that the position of the center of
gravity is located at a position between the head slider and the
vertical rotation axis.
[0016] It is further preferred that when the position of the center
of gravity is at a position which substantially satisfies
L.sub.2<M.sub.1.times.L.sub.1/M.sub.2, where M.sub.1 is a mass
at a load point to the head slider, M.sub.2 is a mass at the
position of the center of gravity, L.sub.1 is a distance between a
load point to the head slider and the vertical rotation axis,
L.sub.2 is a distance between the vertical rotation axis and the
position of the center of gravity, an ABS of the head slider is set
so that negative pressure occurring to the ABS due to rotation of
the recording medium is not less than a product of an inertial
force obtained from a mass of a part from the position of center of
gravity of the head arm assembly to the head slider and an applied
impact acceleration.
[0017] It is still further preferred that the horizontal rotation
axis is provided at a horizontal bearing part located at a midpoint
of the arm member, and the vertical rotation axis includes a
protuberance provided in the vicinity of the horizontal bearing
part.
[0018] It is preferred that the load generation unit includes a
leaf spring connected to the horizontal bearing part and to the arm
member.
[0019] It is also preferred that the arm member includes a support
arm having rigidity, and a flexure having elasticity, which is
supported at one end section of the support arm and for controlling
a flying attitude of the head slider, and the head slider is fixed
on the flexure. In this case, preferably the arm member further
includes a load beam having rigidity and including a load
protrusion for applying load to the head slider, the flexure being
fixed on the load beam.
[0020] Further objects and advantages of the present invention will
be apparent from the following description of the preferred
embodiments of the invention as illustrated in the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view schematically illustrating a
construction of an HAA in a preferred embodiment according to the
present invention;
[0022] FIG. 2 is an exploded perspective view illustrating the HAA
in FIG. 1 and its mounting part;
[0023] FIG. 3 is an exploded perspective view illustrating the part
of the HGA in FIG. 1;
[0024] FIG. 4 is a side view schematically illustrating a
construction of the HAA in FIG. 1;
[0025] FIG. 5 is a view illustrating a position of center of
gravity to be displaced with use of a model of simple material
particles and a beam without having a mass;
[0026] FIG. 6A is a characteristic chart illustrating a result of
simulating a dimple load with respect to an impact acceleration
applied in a Z-direction;
[0027] FIG. 6B is a characteristic chart illustrating a result of
simulating a reactive force at a vertical rotation axis position
with respect to the impact acceleration applied in the Z-axis
direction;
[0028] FIG. 7A is a characteristic chart illustrating a result of
simulating a dimple load with respect to the impact acceleration
applied in the Z-axis direction;
[0029] FIG. 7B is a characteristic chart illustrating a result of
simulating the reactive force at the vertical rotation axis
position with respect to the impact acceleration applied in the
Z-axis direction;
[0030] FIG. 8A is a characteristic chart illustrating a result of
simulating the dimple load with respect to the impact acceleration
applied in the Z-axis direction;
[0031] FIG. 8B is a characteristic chart illustrating a result of
simulating the reactive force at the vertical rotation axis
position with respect to the impact acceleration applied in the
Z-axis direction;
[0032] FIG. 9A is a characteristic chart illustrating a result of
simulating the dimple load with respect to the impact acceleration
applied in the Z-axis direction;
[0033] FIG. 9B is a characteristic chart illustrating a result of
simulating the reactive force at the vertical rotation axis
position with respect to the impact acceleration applied in the
Z-axis direction;
[0034] FIG. 10A is a characteristic chart illustrating a result of
simulating the dimple load with respect to the impact acceleration
applied in the Z-axis direction;
[0035] FIG. 10B is a characteristic chart illustrating a result of
simulating the reactive force at the vertical rotation axis
position with respect to the impact acceleration applied in the
Z-axis direction;
[0036] FIG. 11 is a view illustrating the constitution of the
present invention more generally;
[0037] FIG. 12 is a view illustrating the constitution of the
present invention more generally;
[0038] FIG. 13 is a view illustrating the constitution of the
present invention more generally; and
[0039] FIG. 14 is a view illustrating the constitution of the
present invention more generally.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] FIG. 1 schematically illustrates a construction of an HAA in
a preferred embodiment of the present invention, FIG. 2 illustrates
the HAA and a mounting part thereof, FIG. 3 illustrates a part of a
head gimbal assembly (HGA) thereof, and FIG. 4 schematically
illustrates a construction of the HAA. It should be noted that
FIGS. 1 and 3 are views of the HAA seen from below (a side facing a
magnetic disk), and FIG. 2 is a view of the HAA seen from the
opposite direction from that in FIGS. 1 and 3.
[0041] In these drawings, reference numeral 10 denotes a support
arm having high rigidity, 11 denotes a load beam also having high
rigidity with its base section fixed to a top end section of the
support arm 10, 12 denotes a flexure which is fixed to a top end
section of the load beam 11 and has elasticity to control a flying
attitude of a magnetic head slider 13, 13 denotes the magnetic head
slider which is fitted to a tip end of the flexure 12 and includes
at least one magnetic head element, 14 denotes a leaf spring for
generating a load applied to the magnetic head slider 13, 15
denotes a fixing member for this leaf spring 14, 16 denotes a
horizontal bearing part (bearing housing) for rotationally moving
the support arm 10 in a direction parallel with the surface of a
magnetic disk 17, 18 denotes a coil assembly which has a coil 19
for a VCM and is mounted to the support arm 10, 20 denotes a
mounting spacer, and 21 denotes a nut, respectively.
[0042] The support arm 10 is constructed by a metal plate member
having sufficient rigidity, for example, a stainless steel plate
(for example, SUS304TA) about 330 .mu.m thick, or a resin plate
member.
[0043] The load beam 11 is constructed by a metal plate member
having sufficient rigidity, for example, a stainless steel plate
(for example, SUS304TA) about 40 .mu.m thick. The load beam 11 and
the support arm 10 are fixed by pinpoint fixation by a plurality of
welded points with use of a laser beam or the like when the support
arm 10 is a metal plate member.
[0044] The flexure 12 is constructed so as to give suitable
stiffness to the magnetic head slider 13 pressed and loaded by a
dimple 11a being a protuberance for applying a load provided at a
top end section of the load beam 11. The flexure 12 is constructed
by a stainless steel plate (for example, SUS304TA) about 25 .mu.m
thick in this embodiment. The flexure 12 and the load beam 11 are
fixed by pinpoint fixation by a plurality of welded points with use
of a laser beam or the like.
[0045] The leaf spring 14 is formed of a metal leaf spring material
in substantially a circular shape or substantially a semicircular
shape, and its thickness and quality are suitably selected so as to
be able to give a desired load to the magnetic head slider 13. In
this embodiment, the leaf spring 14 is constructed by a stainless
steel plate (for example, SUS304TA) about 40 .mu.m thick. The leaf
spring 14 is placed to be coaxial with the fixing member 15, a
mounting hole 10a of the support arm 10 and the bearing housing 16,
both end sections of the semicircular shape are fixed to the
support arm 10, and a central portion is fixed to the bearing
housing 16 via the fixing member 15. Accordingly, the support arm
10 is supported by the bearing housing 16 via the leaf spring 14. A
rotation axis of the bearing housing 16 is a horizontal rotation
axis 25a of the support arm 10, accordingly, the HAA, and the
bearing housing 16 and the support arm 10 rotationally move
together in the horizontal direction with this rotation axis 25a as
the center.
[0046] The fixing member 15 is formed of a metal plate with high
rigidity in substantially a semicircular shape, and in this
embodiment, it is constructed by, for example, a stainless steel
plate (for example, SUS304TA) about 100 .mu.m thick.
[0047] A pair of protuberances, namely, pivots 22 as shown in FIG.
4 are provided on an under surface (surface on the side of the
magnetic disk) of a flange portion 16a of the bearing housing 16. A
pair of these pivots 22 are provided at such locations as they are
axially symmetric with respect to a center axis that is a center in
a longitudinal direction (the direction to connect the mounting
part of the magnetic head slider and the coil of the VCM) of the
support arm 10, and a straight line connecting both of them passes
through an axial center of the bearing housing 16, and they are
constructed so that tip ends of these pivots 22 abut to the support
arm 10. Consequently, the support arm 10 is supported by the leaf
spring 14 in the state in which it abuts to the tip ends of the
pivots 22 and is axially supported, and the support arm 10 is
biased in a direction orthogonal to the surface of the magnetic
disk 17. In this case, the straight line connecting the tip ends of
a pair of the pivots 22 becomes a vertical rotation axis 25b of the
support arm 10, accordingly, the HAA.
[0048] The leaf spring 14 provides an elastic force in the
direction shown by an arrow 23 to the support arm 10 having
rigidity. Thus, the support arm 10 rotationally moves around
fulcrums of the pivots 22 to move the dimple 11a of the load beam
11 having rigidity in the direction of an arrow 24 causing that a
load is applied to the magnetic head slider 13.
[0049] According to this construction, the support arm 10 and the
load beam 11 can be constructed by members with high rigidity, and
therefore resistance against the impact applied form outside can be
enhanced. In addition, a resonance frequency can be increased by
using the arm with high rigidity, thus making it possible to
perform positioning with high precision at a high speed without
causing an unnecessary vibration mode.
[0050] The important point in this embodiment is that a position of
a center of gravity of the HAA is displaced to a predetermined
position 26 nearer to the VCK coil 19 than the vertical rotation
axis 25b that is the pivots 22, on the axis line of the arm member
10. The position of the center of gravity is deviated on the axis
line of the arm member 10 without conforming to the vertical
rotation axis 25b that is the fulcrum, whereby it is made possible
to keep the load applied to the magnetic head slider 13
substantially constant irrespective of a positive and negative
direction and a value of the impact acceleration applied from
outside, and it becomes possible to enhance impact resistance
dramatically.
[0051] The position of the center of gravity to be displaced will
be explained using a model of the simple particles and the beam
having no mass, shown in FIG. 5.
[0052] Here, if it is assumed that point A is a load application
point to the magnetic head slider 13, point B is a fulcrum, point C
is a center of gravity, an impact acceleration applied from an
outside is .alpha., a gravitational acceleration is G, a distance
between the point A and the point B is L.sub.1, a distance between
the point B and the point C is L.sub.2, a force a particle M.sub.1
exerts on the point A is Fa, a force a particle M.sub.2 exerts on
the point A is Fa', and a force the particle M.sub.2 generates at
the point C is Fc,
Fa=M.sub.1.times..alpha.
[0053] Fa'=Fc.times.L.sub.2/L.sub.1. Since a change in a load at
the point A at the time of the application of the impact
acceleration is Fa-Fa', if this is zero, the load to the magnetic
head slider does not change even if the impact acceleration is
applied. Accordingly,
(M.sub.1-M.sub.2.times.L.sub.2/L.sub.1).times.(.alpha.-G)=0
[0054] becomes this condition. Namely, the position of the center
of gravity may be any position if only it substantially satisfies
L.sub.2=M.sub.1.times.L.sub.1/M.sub.2.
[0055] FIGS. 6A, 7A, 8A, 9A and 10A respectively illustrate the
simulation results of loads (dimple loads) applied to the magnetic
head slider with respect to impact acceleration applied in a Z-axis
direction (a direction orthogonal to the magnetic disk surface) of
the models with positions of center of gravity set at different
positions from one another. FIGS. 6B, 7B, 8B, 9B and 10B
respectively illustrate the simulation results of reaction forces
(reaction forces at fulcrums that are pressing sections) at
vertical rotation axis positions with respect to the impact
acceleration applied in the Z-axis direction (the direction
orthogonal to the magnetic disk surface) of the models with the
positions of the center of gravity set at the different positions
from one another similarly to the above.
[0056] The models used are assumed to be metal springs 80 .mu.m
thick and 2 mm wide, which meet the stress condition (<60
kgf/mm.sup.2), and obtain the reaction force with the amount
pressed in the Z-axis direction at the fulcrums being fixed at 70
.mu.m.
[0057] FIGS. 6A and 6B are the cases of the model with the position
of the center of gravity being displaced to the magnetic head
slider by 1.3 mm from the vertical rotation axis (fulcrum), FIGS.
7A and 7B are the cases of the model with the position of the
center of gravity being located at the same position as the
fulcrum, FIGS. 8A and 8B are the cases of the model with the
position of the center of gravity being displaced to the VCM by
0.036 mm from the fulcrum, FIGS. 9A and 9B are the cases of the
model with the position of the center of gravity being displaced to
the VCM by 0.087 mm from the fulcrum, and FIGS. 10A and 10B are the
cases of the model with the position of the center of gravity being
displaced to the VCM by 1.51 mm from the fulcrum.
[0058] In case that the position of the center of gravity is
displaced to the magnetic head slider from the fulcrum, in case
that the position of the center of gravity is made to correspond to
the fulcrum, and in case that the position of the center of gravity
is slightly displaced to the VCM from the fulcrum as shown in FIGS.
6A to 8B, the load (dimple load) applied to the magnetic head
slider changes depending upon the values of the impact acceleration
applied from outside.
[0059] On the other hand, in case that the position of the center
of gravity is displaced to the VCM by about 0.087 mm from the
fulcrum as shown in FIGS. 9A and 9B, the original load by the leaf
spring 14, a force directly applied due to the applied impact
acceleration, and the load given by the rotational moment of the
force occurring to the center of gravity due to the applied impact
acceleration are applied to the load point of the magnetic head
slider with a balance being kept between them. Consequently, the
dimple load is substantially kept constant regardless of the
negative and positive direction and the value of the impact
acceleration applied from outside, and therefore it becomes
possible to enhance resistance against impact dramatically.
[0060] Further, in case that the position of the center of gravity
is further displaced to the VCM side as shown in FIGS. 10a and 10b,
the dimple load is changed in the reverse direction depending upon
the value of the impact acceleration applied from outside.
[0061] As described above, by displacing the position of the center
of gravity from the vertical rotation axis to the predetermined
position, the resistance against impact of the HAA can be
substantially improved. On the other hand, by adjusting the
displacement amount and the positive and negative direction of the
position of the center of gravity, the load property applied to the
head slider with respect to the impact acceleration applied from
outside can be changed, and therefore it becomes possible to
compensate positive pressure or negative pressure occurring to the
ABS of the magnetic head slider by this displacement amount. As a
result, the degree of freedom of the ABS design of the magnetic
head slider is substantially improved, and it also becomes possible
to obtain a desired flying property with respect to the head slider
with a very small ABS area.
[0062] More generally, the weight and the position of the center of
gravity of the entire HAA is set so that a force F.sub.MA, which is
applied to the magnetic head slider 113 by a rotational moment
M.sub.A occurring based on an applied impact acceleration
.alpha..sub.A and displacement of the position 110 of the center of
gravity from the fulcrum position 111, becomes negative pressure
F.sub.NE, which occurs to the ABS of this magnetic head slider 113,
or less, when a position of center of gravity 110 is displaced to
the VCM coil 112 from a pivot (fulcrum) position 111 so that
L.sub.2>M.sub.1.times.L.sub.1/M.sub.2 as shown in FIG. 11 (where
M.sub.1: mass at the load point to a magnetic head slider 113,
M.sub.2: mass at a position 110 of center of gravity, L.sub.1:
distance between a load point to the magnetic head slider 113 and
the fulcrum 111, L.sub.2: distance between the fulcrum 111 and the
position 110 of the center of gravity).
[0063] When the position of the center of gravity is displaced to
the VCM under the condition of
L.sub.2>M.sub.1.times.L.sub.1/M.sub.2 as described above, with
respect to the impact acceleration applied in the reverse
direction, the weight and the position of the center of gravity of
the entire HAA are set so that a force F.sub.MB, which is applied
to the magnetic head slider 113 by a rotational moment M.sub.B
occurring based on the impact acceleration .alpha..sub.B and
displacement of the position 110 of the center of gravity from the
fulcrum position 111, becomes positive pressure F.sub.po, which
occurs to the ABS of this magnetic head slider 113, or less, as
shown in FIG. 12. In other words, the ABS of the magnetic head
slider 113 is designed so that the positive pressure F.sub.PO,
which is not less than the product of an inertial force obtained
from the mass of the part from the position 110 of the center of
gravity to the magnetic head slider 113 and the applied impact
acceleration .alpha..sub.B, occurs.
[0064] The weight of the entire HAA and the position of the center
of gravity are set so that a force F.sub.MA, which is applied to
the magnetic head slider 133 by a rotational moment M.sub.A
occurring based on an applied impact acceleration .alpha..sub.A and
displacement of the position 130 of the center of gravity from the
fulcrum position 131, becomes positive pressure F.sub.po, which
occurs to the ABS of this magnetic head slider 133, or less, when a
position 130 of center of gravity is displaced a the magnetic head
slider 133 from a fulcrum position 131 so that
L.sub.2<M.sub.1.times.L.sub.1/M.sub.2 (where M.sub.1: mass at
the load point to the magnetic head slider 133, M.sub.2: mass at a
position 110 of center of gravity, L.sub.1: distance between a load
point to the magnetic head slider 133 and the fulcrum 111, L.sub.2:
distance between the fulcrum 111 and the position 110 of the center
of gravity), or when the position 130 of the center of gravity is
displaced to a VCM coil 132 (not shown), as shown in FIG. 13.
[0065] When the position of the center of gravity is displaced to
the magnetic head slider or the VCM under the condition of
L.sub.2<M.sub.1.times.L.sub.1/M.sub.2 as described above, with
respect to the impact acceleration applied in the reverse
direction, the weight and the position of the center of gravity of
the entire HAA are set so that a force F.sub.MB, which is applied
to the magnetic head slider 133 by a rotational moment M.sub.B
occurring based on the impact acceleration .alpha..sub.B and
displacement of the position 130 of the center of gravity from the
fulcrum position 131, becomes negative pressure F.sub.NE, which
occurs to the ABS of this magnetic head slider 133, or less, as
shown in FIG. 14. In other words, the ABS of the magnetic head
slider 133 is designed so that the negative pressure F.sub.NE,
which is not less than the product of an inertial force obtained
from the mass of the part from the position 130 of the center of
gravity to the magnetic head slider 133 and the applied impact
acceleration .alpha..sub.B, occurs.
[0066] The present invention is explained with use of the HAA
including the thin film magnetic head element, but the present
invention is not limited only to the HAA like this, but it is
obvious that the present invention is applicable to the HAA
including the head element such as, for example, an optical head
element other than a thin-film electromagnetic head element.
[0067] Many widely different embodiments of the present invention
may be constructed without departing from the spirit and scope of
the present invention. It should be under stood that the present
invention is not limited to the specific embodiments described in
the specification, except as defined in the appended claims.
* * * * *